MADRID (AFP) - World number one Novak Djokovic comfortably preserved his 10-year undefeated Davis Cup singles record on Wednesday (Dec 1) to keep Serbia alive in their quarter-final against Kazakhstan.

Djokovic eased past 36th-ranked Alexander Bublik 6-3, 6-4 in 77 minutes to leave the tie resting on the outcome of the doubles rubber.

Twenty-time Grand Slam title winner Djokovic has not lost a singles match in the competition since retiring against Juan Martin del Potro in Serbia's 2011 semi-final defeat to Argentina.

Serbia, the 2010 champions, are bidding to make the semi-finals of the Davis Cup for the fifth time.

Djokovic is now due to team up with Nikola Cacic in the doubles against Andrey Golubev and Aleksandr Nedovyesov.

"We haven't finished the job - I hope that we can win the doubles," said Djokovic.

The eventual winners of the tie will face Croatia in the semi-finals.

Earlier Wednesday, Mikhail Kukushkin saved four match points to defeat Miomir Kecmanovic to give the Kazakhs the opening point of the quarter-final.

Kukushkin, the world 182, triumphed over 69th-ranked Kecmanovic 7-6 (7/5), 4-6, 7-6 (13/11) after more than three hours on court.

Kecmanovic, preferred by Serbia captain Viktor Troicki over higher-ranked Dusan Lajovic and Filip Krajinovic, had been on course for victory after winning seven games in a row on his way to a 3-0 lead in the decider.

"You know this kind of match for sure is going to be special in my life," said the 33-year-old Russian-born Kukushkin.

"I don't even know what was the score in the tiebreak. This is why we love the Davis Cup, it's about these kind of matches.

"I'm so honoured to play for my country. Our fans are the best in the world. They gave that kind of support for so many years. I was fighting a lot, it was such a difficult match."

Germany will face either Sweden or Russia in the other semi-final on Friday with the final also being played in Madrid on Sunday.